The present invention relates to an airbag for a vehicle safety restraint and particularly to a method of folding a uninflated airbag for storage in the vehicle. The method applies primarily to a driver's side airbag but can easily be adapted to a passenger side bag, to a side impact bag or to other forms of airbag.
Airbags are relatively bulky accessories and there is a desire to minimise the space occupied by the folded bag in the vehicle. This is particularly true of a driver's side airbag which is usually housed in the hub of a steering wheel and thus must fit into a very small space, particularly in the smaller steering wheels used in sport model vehicles or other customised designs. Traditionally an uninflated airbag is folded in consecutive overlapping folds until it occupies the requisite space. Often pressure and sometimes heat is applied to compact it further.
The present invention aims to provide a method by which an airbag can be folded into a smaller diameter housing giving a more compact module than is possible with traditional methods.
According to the present invention there is provided a method of folding an airbag comprising laying the airbag generally flat, making folds in the flat airbag to form a polygon in plan view, folding all of the sides of the polygon upwardly and inwardly of the polygon considered in plan view so that at least one point on each side meets a point on at least one other side at a position generally above the centre of the polygon so that the corners of the polygon form upstanding ears, and subsequently rolling the upstanding corner ears of the polygon to form the airbag into a cylindrical shape.
According to a preferred embodiment of symmetry or relative to lines of symmetry of the first formed polygon, for example lying at 45.degree. and less to respectively the first and second lines a method is provided of folding an airbag wherein the step of making folds in the flat airbag comprises the airbag folding subsequently folding the airbag along parallel lines spaced equidistantly on opposite sides of a line of symmetry, perpendicular to the first line of symmetry. These folding steps may be repeated to form a smaller polygon. The further folding may be relative to the same lines of symmetry or relative to lines of symmetry of the first formed polygon, for example lying at 45.degree. and less to respectively the first and second lines.
According to a preferred embodiment a method is provided wherein the corner turning or bending step is accompanied or preceded by a step of stretching the corner ears in a radially outward direction, and/or of flattening the corner ears by applying force at opposite sides of each ear, particularly at those parts of the corner ears which bulge or arch outwardly.